The present invention relates to a method for making aromatic ether imides by effecting the condensation of a phenoxide salt with a nuclear-substituted phthalimide in the presence of a nonpolar solvent and a phase transfer catalyst. More particularly, the present invention relates to a method for making an aromatic ether phthalimide or an aromatic bis (ether phthalimide).
Prior to the present invention, methods involving the condensation of an alkali metal phenoxide with a nuclear substituted phthalimide as shown by Heath et al U.S. Pat. Nos. 3,879,428, 3,957,862 and 3,956,320, assigned to the same assignee as the present invention, or Meyers U.S. Pat. No. 3,965,125, were generally based on the use of a dipolar aprotic solvent to facilitate reaction. Those skilled in the art know that it is often economically unattractive to effect the synthesis of various organic materials using dipolar aprotic solvents because such solvents are expensive and often subject to a variety of chemical side reactions which render them useless for recycling.
The present invention is based on the discovery that aromatic ether imides of the formula, ##STR1## can be made without the use of a dipolar aprotic solvent, by effecting the reaction between the alkali metal phenoxide salt or diphenoxide salt and the nuclear substituted phthalimide in a nonpolar organic solvent and in the presence of a phase transfer catalyst, where R is a monovalent radical selected from hydrogen, a C.sub.(1-8) alkyl radical and C.sub.(6-13) aryl radical, R.sup.1 is a C.sub.(6-30) aromatic organic radical, and a is an integer equal to 1 or 2, and when a is 1, R.sup.1 is monovalent and when a is 2,R.sup.1 is divalent.